External fixator system

Abstract

An external fixation frame for correcting a bone deformity includes a first fixation ring and a second fixation ring. A posterior adjustable length strut couples a posterior portion of the first fixation ring to a posterior portion of the second fixation ring and has universal joint. Medial and lateral adjustable length struts couple medial and lateral portions of the first fixation ring to medial and lateral portions of the second fixation ring respectively, each of the medial and lateral adjustable length struts including a constrained hinge joint. The fixation frame also includes a half ring coupled to the second fixation ring.

The invention claimed is: 
     
       1. An external fixation frame for correcting a bone deformity, comprising:
 a top fixation ring; 
 a bottom fixation ring; 
 a medial adjustable length strut coupling a medial portion of the top fixation ring to a medial portion of the bottom fixation ring; 
 a lateral adjustable length strut coupling a lateral portion of the top fixation ring to a lateral portion of the bottom fixation ring; 
 a half ring coupled between the top and bottom fixation rings; and 
 a rocker member coupled to a bottom surface of the bottom fixation ring. 
 
     
     
       2. The external fixation ring of  claim 1 , wherein the half ring comprises a lateral end portion, a medial end portion, and an arcuate body portion connecting the lateral end portion to the medial end portion. 
     
     
       3. The external fixation frame of  claim 1 , wherein the bottom fixation ring is U-shaped including a medial anterior projection, a lateral anterior projection, and a rounded posterior section connecting the medial anterior projection to the lateral anterior projection. 
     
     
       4. The external fixation frame of  claim 3 , wherein a first fastening member couples the medial end portion of the half ring to the medial anterior projection of the bottom fixation ring and a second fastening member couples the lateral end portion of the half ring to the lateral anterior projection of the bottom fixation ring. 
     
     
       5. The external fixation frame of  claim 3 , wherein the rocker member is a first rocker member coupled to the bottom surface of the medial projection of the bottom fixation ring, and wherein a second rocker member is coupled to the bottom surface of the lateral projection of the bottom fixation ring. 
     
     
       6. The external fixation frame of  claim 1 , wherein the rocker member comprises a curved body portion with at least one connecting element projecting proximally from the curved body portion and configured to mate with an aperture in the bottom fixation ring in order to couple the rocker member to the bottom fixation ring. 
     
     
       7. The external fixation frame of  claim 6 , wherein the connecting element comprises:
 a main body portion extending through an aperture in the curved body portion of the rocker member; and 
 a distal flange extending distally of the main body portion, the distal flange configured to contact a corresponding shoulder portion of the aperture in the curved body portion. 
 
     
     
       8. The external fixation frame of  claim 7 , wherein the rocker member further comprises a ground-contacting rounded distal portion coupled to a distal portion of the curved body portion of the rocker member, the ground-contacting rounded distal portion having a textured ground-contacting surface. 
     
     
       9. The external fixation frame of  claim 1 , wherein the rocker member comprises an anterior portion and a posterior portion, and wherein at least one fastener projects proximally from each of the anterior and posterior portions and is received within an aperture in the bottom fixation ring in order to couple the rocker member to the bottom fixation ring. 
     
     
       10. The external fixation frame of  claim 1 , wherein the rocker member comprises a curved body portion with at least one connecting element projecting proximally from the curved body portion and configured to mate with an aperture in the bottom fixation ring in order to couple the rocker member to the bottom fixation ring. 
     
     
       11. The external fixation frame of  claim 10 , wherein the connecting element comprises:
 a main body portion extending through an aperture in the curved body portion of the rocker member; and 
 a distal flange extending distally of the main body portion, the distal flange configured to contact a corresponding shoulder portion of the aperture in the curved body portion. 
 
     
     
       12. The external fixation frame of  claim 11 , wherein the rocker member further comprises a ground-contacting rounded distal portion coupled to a distal portion of the curved body portion of the rocker member, the ground-contacting rounded distal portion having a textured ground-contacting surface. 
     
     
       13. The external fixation frame of  claim 1 , wherein the rocker member comprises an anterior portion and a posterior portion, and wherein at least one fastener projects proximally from each of the anterior and posterior portions and is received within an aperture in the bottom fixation ring in order to couple the rocker member to the bottom fixation ring. 
     
     
       14. An external fixation frame for correcting a bone deformity, comprising:
 a top fixation ring; 
 a bottom fixation ring; 
 a medial adjustable length strut coupling a medial portion of the top fixation ring to a medial portion of the bottom fixation ring; 
 a lateral adjustable length strut coupling a lateral portion of the top fixation ring to a lateral portion of the bottom fixation ring; 
 a posterior adjustable length strut coupling a posterior portion of the top fixation ring to a posterior portion of the bottom fixation ring; 
 a half ring coupled between the top and bottom fixation rings; and 
 a rocker member coupled to a bottom surface of the bottom fixation ring. 
 
     
     
       15. The external fixation ring of  claim 14 , wherein the half ring comprises a lateral end portion, a medial end portion, and an arcuate body portion connecting the lateral end portion to the medial end portion. 
     
     
       16. The external fixation frame of  claim 14 , wherein the bottom fixation ring is U-shaped including a medial anterior projection, a lateral anterior projection, and a rounded posterior section connecting the medial anterior projection to the lateral anterior projection. 
     
     
       17. The external fixation frame of  claim 16 , wherein a first fastening member couples the medial end portion of the half ring to the medial anterior projection of the bottom fixation ring and a second fastening member couples the lateral end portion of the half ring to the lateral anterior projection of the bottom fixation ring. 
     
     
       18. The external fixation frame of  claim 16 , wherein the rocker member is a first rocker member coupled to the bottom surface of the medial projection of the bottom fixation ring, and wherein a second rocker member is coupled to the bottom surface of the lateral projection of the bottom fixation ring. 
     
     
       19. An external fixation frame for correcting a bone deformity, comprising:
 a top fixation ring; 
 a u-shaped bottom fixation ring including a medial anterior projection, a lateral anterior projection, and a rounded posterior section connecting the medial anterior projection to the lateral anterior projection; 
 a medial adjustable length strut coupling a medial portion of the top fixation ring to a medial portion of the bottom fixation ring; 
 a lateral adjustable length strut coupling a lateral portion of the top fixation ring to a lateral portion of the bottom fixation ring; 
 a half ring coupled between the top and bottom fixation rings; and 
 first and second rocker members coupled to a bottom surface of the bottom fixation ring, 
 wherein the first rocker member is coupled to the medial projection of the bottom fixation ring and the second rocker member is coupled to the bottom surface of the lateral projection of the bottom fixation ring. 
 
     
     
       20. The external fixation ring of  claim 19 , wherein the half ring comprises a lateral end portion, a medial end portion, and an arcuate body portion connecting the lateral end portion to the medial end portion.